Pre-filled retractable needle injection device

ABSTRACT

A needle-bearing device for injecting medicinal fluid from a pre-filled vial is provided. After use, the needle is retracted into the body of the device to prevent inadvertent contact with the sharpened end of the needle. In one embodiment, the invention provides a manually actuable button that effectuates retraction of the needle after use. In another embodiment, retraction is effectuated automatically after the injection is complete.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.09/528,634 filed Mar. 20, 2000, to be issued on May 27, 2003 as U.S.Pat. No. 6,569,115, which is a continuation-in-part of U.S. applicationSer. No. 09/139,540 filed Aug. 26, 1998, now issued as U.S. Pat. No.6,039,713, and International Application No. PCT/US99/04456 filed Mar.1, 1999. This application also claims priority to U.S. ProvisionalApplication Nos. 60/058,004 filed Aug. 28, 1997, 60/078,233 filed Mar.17, 1998, 60/120,889 filed Feb. 20, 1999, and 60/152,016 filed Sep. 1,1999. Each of the foregoing applications is hereby incorporated hereinby reference as if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to pre-filled vials, ampoules, carpules,or cartridges for administering injections of medicinal fluids topatients. More specifically, the invention relates to such deviceshaving a retractable needle feature for rendering the devicenon-reusable and safely disposable.

BACKGROUND OF THE INVENTION

Various types of medical devices employ a needle for piercing the skinof a patient for diagnostic or therapeutic purposes. One such device isa vial injector. Vial injectors utilize pre-filled vials that have apre-measured dose of medication. The vial injector is used to inject themedication from the vial into a patient.

Handling of such needle-bearing medical devices after the needle iswithdrawn from the patient can result in transmission of variouspathogens, most notably human immune virus (HIV), to uninfected medicalpersonnel, due to an inadvertent needle stick. Accordingly, it isdesirable to provide a device for injecting medication from a pre-filledvial, wherein the injection needle is retracted into the housing of thedevice after use.

There are numerous retractable needle medical devices disclosed in theprior art. Typically, to effectuate retraction, the prior art devicesrequire manual actuation by the operator. In many situations, such as anemergency situation, the operator is distracted or rushed so that themanual step necessary to effectuate retraction is not performed, eitherintentionally or unintentionally. In such instances, the used needleremains exposed, creating a risk of an inadvertent needle stick.Therefore, it would be desirable to provide an automatic needleretraction mechanism in which needle retraction is effectuated by normaloperation of the device without the need to perform a separate manualstep. It is further desirable to provide a device with a limited numberof components so that the device can be produced cost effectively.

SUMMARY OF THE INVENTION

With the foregoing in mind, the present invention provides a medicaldevice for injecting medicinal fluid from a fluid container, such as avial, into a patient. The device includes a needle that is retractedautomatically after use so that the contaminated sharpened tip of theneedle is enclosed within the device to prevent inadvertent needlesticks.

The device includes a hollow housing having a generally open rearwardend forming a socket. A vial containing a quantity of medicinal fluid isadapted to engage the socket. The needle for injecting the fluid isoperable between a projecting position in which the sharpened tip of theneedle projects forwardly from the housing and a retracted positionwherein the sharpened tip is enclosed within the housing. A biasingelement biases the needle toward the retracted position. A needleretainer releasably retains the needle in the projecting position. Theneedle retainer is operable between a locked position and an unlockedposition. In the locked position, the needle retainer releasably retainsthe needle in the projecting position against the bias of the biasingelement. In the unlocked position, the needle is released allowing thebiasing element to displace the needle rearwardly. The vial cooperateswith the needle retainer so that upon forward displacement of the vial,the vial engages the needle retainer displacing the needle retainer fromthe locked position to the unlocked position.

DESCRIPTION OF THE DRAWINGS

All of the objects of the present invention are more fully set forthhereinafter with reference to the accompanying drawings, wherein:

FIG. 1 is a side elevational view of a vial injector having aretractable needle;

FIG. 2 is a side sectional view of the vial injector shown in FIG. 1,taken along line 2-2;

FIG. 3 is a top sectional view of the vial injector shown in FIG. 2,taken along line 3-3;

FIG. 4 is a side sectional view of the vial injector shown in FIG. 2,illustrating the device in a “ready for use” position;

FIG. 5 is a top sectional view of the vial injector shown in FIG. 3,illustrating the device in a “ready for use” position;

FIG. 6 is a side sectional view of the vial injector shown in FIG. 2,illustrating the needle just prior to retraction;

FIG. 7 is a top sectional view of the vial injector shown in FIG. 3,illustrating the needle just prior to retraction;

FIG. 8 is a side sectional view of the vial injector shown in FIG. 2,illustrating the needle after retraction;

FIG. 9 is a top sectional view of the vial injector shown in FIG. 3,illustrating the needle after retraction;

FIG. 10 is an enlarged fragmentary side sectional view of detail A inFIG. 2;

FIG. 11 is an enlarged fragmentary side sectional view of detail B inFIG. 4;

FIG. 12 is an exploded perspective view of the vial injector shown inFIG. 1;

FIG. 13 is a cross-sectional view of an alternate embodiment of amedical device for use in injecting medication from a vial;

FIG. 14 is a cross-sectional view of the device shown in FIG. 13,illustrating the device in a position just prior to release of a safetylatch;

FIG. 15 is a cross-sectional view of the device shown in FIG. 13,illustrating the device in a position just subsequent to release of thesafety latch;

FIG. 16 is a cross-sectional view of the device shown in FIG. 13,illustrating the insertion needle in a retracted position

FIG. 17 is an enlarged fragmentary cross-sectional view of the deviceshown in FIG. 14, illustrating details of the safety latch in a latchedposition; and

FIG. 18 is an enlarged fragmentary view of the device shown in FIG. 15,illustrating details of the safety latch in an unlatched position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1-12 in general and to FIGS. 1-3 specifically,there is shown a vial injector 10 with an attached vial 60 that ispre-filled with medication. The vial injector 10 includes a needle 50with a sharpened tip for inserting the needle into a patient. The needle50 is in fluid communication with the medicine in the vial 60. Bypressing the vial 60 into the vial injector 10, the medicine is expelledfrom the vial and into the patient through the needle 50. After themedicine is administered to the patient, the needle is retracted intobody of the vial injector automatically.

Referring to FIGS. 1-3, the device 10 includes a generally cylindricalhousing 20, a needle 50, a spring 55 biasing the needle rearwardly, anda needle retainer 40 releasably retaining the needle against the bias ofthe spring. The needle is operable between two positions, a projectingposition and a retracted position. In the projecting position, theneedle 50 projects forwardly from the forward end of the housing 20. Inthe retracted position, the needle is retracted into the housing 20 sothat the sharpened tip of the needle is enclosed within the housing toprevent inadvertent contact with the sharpened tip. When the needle isin the projecting position, as shown in FIG. 2, the spring biases theneedle rearwardly toward the retracted position. The needle retainer 40releasably retains the needle in the projecting position, against thebias of the spring. The needle retainer cooperates with the vial 60, sothat when the vial is displaced forwardly during injection of themedicine, the needle retainer automatically releases the needle and theneedle retracts into the housing, as shown in FIGS. 8 and 9.

As shown in FIG. 2, the spring 55 circumscribes the needle 50. A forwardend of the spring bears against the interior of the forward portion ofthe nose 22. The rearward end of the spring bears against the forwardend of the plunger 30.

Referring now to FIGS. 2-3, the elements of the device 10 will bedescribed in greater detail. The housing is generally cylindrical andthe forward end of the housing has a reduced diameter tapered nose 22.The nose 22 has an opening through which the needle 50 projectsoutwardly from the housing 20 so that the sharpened tip of the needlecan be inserted into a patient for administering medication to thepatient. Prior to use, a needle cap encloses the portion of the needle50 projecting from the housing. The rearward end of the housing 20 isopen, forming a cylindrical socket 24 for receiving the vial 60. Twolaterally extended flanges 23 project outwardly from the housing 20,transverse the longitudinal axis of the housing, forming two fingergrips for operating the device. The housing further includes a pair oflocking apertures 26 that cooperate with the needle retainer asdescribed further below.

A plunger 30 is disposed within the housing 20. The needle 50 is fixedlyattached to the plunger 30. Specifically, the plunger 30 is a generallycylindrical element having a central bore. The needle is a double endedneedle, so that both ends of the needle are sharpened. The needle 50 isdisposed within the central bore of the plunger so that the forwardportion of the needle projects forwardly from the plunger and therearward portion of the needle projects rearwardly from the plunger. Theneedle can be attached to the plunger in one of several ways. Forinstance, the needle 50 may be attached to the plunger 30 by an adhesivesuch as a UV curable epoxy. Alternatively, the needle can be molded intothe plunger, which is formed of plastic. The rearward end of the plunger30 forms a stem 32 configured to cooperate with the vial 60, asdiscussed further below.

The plunger 30 is axially displaceable within the housing 20. Prior toretraction, the plunger is retained in a fixed axial position. Theplunger is retained in this fixed position while the medication is beingexpelled from the vial 60. After use, the plunger and the attachedneedle are displaced rearwardly.

The needle retainer 40 is operable between a locked position and anunlocked position. In the locked position, the needle retainer 40releasably retains the plunger 30 and the attached needle 50 in a fixedaxial position so that the needle projects forwardly from the housing20. More specifically, in the locked position the needle retainerengages the housing 20, to retain the plunger 30 and the attached needleagainst the rearward bias of the spring 55. In the unlocked position,the needle retainer allows the plunger 30 and the needle 50 to beretracted rearwardly. More specifically, in the unlocked position, theneedle retainer disengages the housing, so that the spring 55 can propelthe needle and the attached plunger rearwardly.

The needle retainer 40 comprises a pair of the elongated resilient arms42. The arms project forwardly and radially outwardly into engagementwith the locking apertures 26 formed in the side of the housing 20. Theterminal end of each arm forms a locking tab or detent 44. The lockingtabs project into the apertures 26 of the housing 20. Each apertureforms a lip or rim. The locking tabs 44 engage the lip formed by eachaperture. In this way, the locking tabs 44 operate as a pair of latchesto retain the plunger 30 and the attached needle 50 against the bias ofthe spring 55.

Referring again to FIGS. 2 and 4, the rearward end of the housing 20 isgenerally opened, forming a socket for-receiving the vial 60. The vial60 is a generally cylindrical vessel containing an amount of medicinalfluid. In the present instance the vial is formed of a rigid materialsuch as glass. The rearward end of the vial 60 is closed, and theforward end of the vial is sealed by an elastomeric piston or plug 64.The plug 64 is generally cylindrical having a plurality ofaxially-spaced circumferential ribs frictionally and sealingly engagingthe interior of the container to provide a fluid-tight seal, therebypreventing fluid from leaking from the vial. The plug 64 furtherincludes a pierceable septum that is pierceable by the rearward end ofthe needle 50. The septum reseals around the needle 50 after beingpierced, to prevent fluid from leaking from the vial.

The plug 64 is configured to cooperate with the mounting stem 32 of thedevice 10. In the present instance, the mounting stem 32 is a barb andthe plug 60 has a corresponding socket 68. The interior end of the plug64 adjacent the medication includes a recess 65. In this way, apierceable wall is formed in the plug 64 between the recess 65 and thebase of the socket 66. When the vial 60 is mounted on the mounting stem32, the rearward sharpened end of the needle 50 pierces the wall of theplug and extends into the recess 65 formed in the interior of the plug.The recess 65 opens to the interior of the vial 60 so that when theneedle 50 projects into the recess, the needle is in fluid communicationwith the interior of the vial 60, allowing medication to flow from thevial into the needle. After the needle pierces the wall of the plug, thewall forms a fluid-tight seal between the plug 64 and the side of theneedle to prevent medication from leaking into the housing 20.

The plug 64 further includes a socket 66 that matingly engages the barbof the mounting stem. Specifically, the socket includes two radiallyrelieved portions or recesses 67 a, 67 b that mate with the head of thebarb. As shown in FIG. 10, prior to use the vial 60 is mounted onto thestem 32 so that the head of the barb engages the first radial recess 67a in the socket. In this position, the needle does not pierce the septumof the piston. To prepare for use, the medical professional displacesthe vial forwardly relative to the mounting stem 32, as shown in FIG.11, thereby displacing the head of the barb into engagement with thesecond radial recess 67 b in the socket 66. At the same time, the needlepierces the septum, so that the needle is in fluid communication withthe medicament in the vial.

The connection between the vial 60 and mounting stem 32 is preferably aone-way engagement. In other words, when the vial is mounted on themounting stem, the vial can be displaced forwardly relative to themounting stem, but the vial can not be displaced rearwardly relative tothe mounting stem. In this way, the vial cannot be readily removed fromthe mounting stem, such that the vial is substantially permanentlyattached to the mounting stem.

The one-way connection is provided by the rearward-facing taperedshoulder of the barb 32 and the radial recesses 67 a, 67 b in thepiston, and the sharp or square forward facing shoulders of the barb andthe radial recess. The rearward-facing shoulder of the barb and theradial recesses cooperate to permit relative displacement. However, thesquare shoulders operate as stops impeding relative rearwarddisplacement.

In addition, the plug 64 is configured to prevent ejection of fluid whenthe vial 60 is displaced from the first position in which the mountingstem 32 engages the first radial recess 67 a, to the second position inwhich the mounting stem engages the second radial recess 67 b and theneedle 50 pierces the septum. Specifically, the plug 64 includes aflared head 68 or circumferential flange at the forward end. The flaredhead 68 engages the interior of the container 62 when the vial isdisplaced from the first position to the second position. The engagementbetween the flared head and the interior of the container 62 combinedwith the frictional engagement between the piston and the interior ofthe container is greater than the force required to displace the pistonfrom the first position to the second position. Accordingly, thecontainer does not move relative to the piston when the vial isdisplaced into the second position in preparation for an injection.Preventing the container 62 from displacing relative to the piston 64,prevents fluid from being expelled when the needle 50 pierces the septumin the piston.

The medication is expelled from the vial 60 by moving the vial axiallyforwardly to advance the vial. The plug 64 is mounted on the mountingstem 32 so that the plug remains stationary while the vial 60 isadvanced. The plug 64 is configured to form a sliding fit with theinterior of the vial so that the vial can slide over the-plug to expelthe medication from the vial. Additionally, the circumferential ribsmaintain a fluid-tight seal between the plug and the vial while the vialslides over the plug.

As the vial 60 is advanced, the medication in the vial flows out of thevial and into the needle. The medication is expelled from the needleinto the patient. As described further below, after the medication isinjected into the patient, the needle 50 is retracted into the housing20 so that the forward sharpened tip of the needle is enclosed withinthe housing 20.

Referring now to FIGS. 4-9, the actuation of the needle retainer 40 ismost clearly shown. The forward end of the container 62 forms a rim. Asthe container 62 is axially advanced, the rim of the container 62 isdisplaced into engagement with the arms 42 of the needle retainer 40.The container 62 is configured so that the distance between the rearwardend of the plug 64 and the rearward end of the vial corresponds to thedistance between the rim of the vial and the needle retainer arms 42when the vial is mounted on the mounting stem 32. In this way, the rimof the container 62 engages the needle retainer arms 42 whensubstantially all of the medication is expelled from the vial 60.

After the rim of the container 62 engages the needle retainer arms 42,continued axial advancement of the container displaces the arms 42radially inwardly so that the locking tabs 44 are displaced inwardly,disengaging the locking tabs 44 from the locking apertures 26 of thehousing 20. In this way, the vial operates as an actuator such thataxial advancement of the vial displaces the needle retainer into theunlocked position. The spring is of sufficient force to overcome thefriction between the locking tabs 44 and the interior of the housing 20.After the needle retainer is in the unlocked position and the userreleases the vial, the spring 55 propels the needle 50 rearwardly untilthe forward sharpened tip of the needle is enclosed within the housing20.

As shown in FIGS. 8 and 9, when the needle 50 is retracted, the needle,the plunger 30, and the vial 60 are displaced rearwardly together.Accordingly, preferably the device 10 includes a mechanism for limitingthe rearward travel of the retracted elements. In addition, preferablythe device includes an element for limiting the forward displacement ofthe needle after retraction to prevent the contaminated needle frombeing re-extended from the housing.

Referring now to FIGS. 3, 5, 7 and 9, the device 10 includes a pair ofguide arms 38 that cooperate with a pair of alignment channels orgrooves 28 formed in the interior wall of the housing. The guide arms 38are integrally formed with the plunger 30, and project radiallyoutwardly into engagement with the alignment grooves 28 formed in thehousing 20. Each guide arm comprises an axially elongated portion, whichpreferably is generally parallel to the housing walls. The forward endof each arm turns outwardly transverse the axis of the housing, and intoengagement with the alignment groove 28 to constrain the plunger againstcircumferential displacement relative to the housing. In this way, theplunger is limited to axial displacement.

The axially elongated component of each guide arm 38 is spaced radiallyinwardly from the inner wall of the housing to create a clearance space.Preferably, the radial thickness of the clearance space is greater thanthe thickness of the wall of the vial container 62. In this way, whenthe vial 60 is advanced, the vial does not engage the guide arms 38.

Each alignment groove 28 is substantially parallel to the axis of thehousing 20, and terminates prior to the rearward edge of the housing.The rearward portion of each alignment groove 28 intersects a lockoutwindow formed in the wall of the housing. Each guide arm 38 engages thecorresponding lockout window at the rearward-most point of retraction,thereby retaining the corresponding guide arm 38 against forwarddisplacement, so that the plunger and the attached needle cannot bedisplaced forwardly.

Preferably, the device further includes a front cap 33 and a rear cap35. The front cap 33 covers the font end of the housing 20 and the frontend of the needle 50 prior to use to prevent inadvertent contact withthe needle or contamination of the needle. In addition, the front cap 33operates as a seal to seal the forward end of the housing againstentrance of contaminants. Specifically, a plurality of spaced-apartcircumferential ribs 31 project from the interior surface of the frontcap. The ribs 31 engage the exterior surface of the housing in sealingengagement. In this way, the front cap 33 prevents the migration ofcontaminant into the housing 20 through either the openings 26 thatengage the needle retainer 40, or the forward opening in the nose 22 ofthe housing 20.

Similarly, the rear cap 35 covers the rearward end of the housing 20 andthe vial 60. The rear cap 35 operates as a seal to seal the rearward endof the housing against entrance of contaminants. In addition, the rearcap 35 engages a circumferential flange on the housing 20 that limitsthe forward displacement of the rear cap. In this way, the rear cap 35prevents inadvertent displacement of the vial 60, which could cause thepiston septum to be inadvertently pierced and inadvertent ejection ofthe fluid from the vial. Like the front cap 33, the rear cap 35 includesa plurality of spaced-apart circumferential ribs 37 that projectradially inwardly from the interior surface of the rear cap. The ribs 37engage the exterior of the housing in sealing engagement. In this way,the rear cap prevents the migration of contaminants into the housingthrough the rearward open end of the housing.

Configured as described above, the device 10 operates as follows. Thefront and rear caps 33, 35 are removed to expose the needle 50 and thevial 60. Prior to use, the needle 50 is disposed in the projectingposition so that the sharpened forward tip of the needle projectsforwardly from the housing 20. Preferably, the device 10 is shipped withthe vial 60 already mounted on the device so that the first recess 67 aof the socket 66 on the plug 64 is already engaging the mounting stem32. Alternatively, the device may be shipped separately from the vial 60so that the vial must first be attached to the device. The vial 60 isthen displaced forwardly relative to the mounting stem 32 so that themounting stem engages the second recess 67 b and the needle pierces theseptum of the plug 64.

The needle 50 is then inserted into the patient and the vial 60 isdepressed to axially advance the vial, thereby injecting the medicinalfluid from the vial into the patient. At the end of the injectionstroke, the vial engages the needle retainer 40, displacing the needleretainer arms 42 radially inwardly thereby actuating the needle retainerto the unlocked position. However, the needle does not retract until themedical professional releases the vial. Once the vial is released, thespring 55 then propels the needle 50 rearwardly so that the contaminatedforward sharpened tip of the needle is enclosed within the housing.Accordingly, the medical professional can retain pressure on the vialuntil after the needle is withdrawn from the patient. The medicalprofessional can then release his or her finger pressure on the vial sothat the spring automatically retracts the needle. Alternatively, themedical professional can release his or her finger pressure on the vialafter the needle retainer is unlocked and while the needle is stillinserted into the patient. The spring 55 then retracts the needle 50,thereby withdrawing the needle from the patient and into the housing.

Referring now to FIGS. 13-18 in general, and to FIG. 13 specifically, analternate embodiment of a vial injector 110 is shown. The vial injector110 includes two needles, an insertion needle 114 and a rearward needle116 that pierces a plug 190 that seals the vial 170. The insertionneedle 114 is operable to inject medication into a patient, and isreleasably retained by a needle retainer 150. An actuator 130 cooperateswith the needle retainer 150 such that forward axial displacement of theactuator 130 causes the needle retainer 150 to release the insertionneedle 114. A spring 160 then propels the insertion needle 114rearwardly so that the sharpened tip of the needle is located within thevial injector.

The vial injector 110 includes a generally cylindrical hollow barrel 120having a forward reduced diameter tip 122. The tip 122 is generallyclosed having a orifice through which the insertion needle 114 projects.The rearward end 124 of the barrel 120 is generally open and is sized toreceive the vial 170.

The needle retainer 150 is positioned within the forward end of thebarrel 120, adjacent the tip 122. The needle retainer 150 releasablyretains the insertion needle 114 so that the insertion needle projectsforwardly from the barrel 120 as illustrated in FIG. 13. The needleretainer 150 can be attached to the barrel 120 in a variety of ways,including ultrasonic welding, epoxy, or a snap fit. In the presentinstance, the needle retainer 150 is attached to the barrel 120 by wayof a snap fit.

The insertion needle 114 projects through an axial bore in the needleretainer 150. The needle retainer includes a generally cylindrical bodyportion 152 at the forward end of the needle retainer and a plurality ofaxially elongated fingers 154 that releasably retain the insertionneedle 114. The fingers 154 have radially inwardly directed protrusionsforming a constricted portion in the bore of the needle retainer.Preferably, the surface of each protrusion is configured to conform tothe outer surface of insertion needle 114 to maintain the needle inaxial alignment with the needle retainer 150. The surfaces of theprotrusions preferably form a continuous surface within the interior ofthe needle retainer to improve engagement with the insertion needle. Thefingers 154 are secured or bonded to the outer surface of the insertionneedle 114 using an adhesive such as an epoxy. The needle retainer 150preferably includes four fingers 154, but one or more fingers 154 may beemployed depending on such factors as the size of the device and thenature of the biasing member. The exterior of the needle retainer 150 isprovided with longitudinal grooves or score lines between the fingers154 to facilitate separation of the fingers when retraction of theneedle is actuated.

Alternatively, the needle retainer 150 can utilize a latchingarrangement rather than being releasably bonded to the needle. In thelatching arrangement, a block is affixed to the insertion needle 114.The ends of the needle retainer fingers 154 form inwardly directedlatches that engage the block to releasably retain the insertion needle.

The needle retainer 150 retains the insertion needle 114 against therearward bias of a spring 160. In the present instance, the spring 160is a coil spring that circumscribes the insertion needle 114. As shownin FIG. 13, the forward end of the spring 160 bears against the interiorof the barrel tip 122. The rearward end of the spring 160 is attached tothe insertion needle 114, preferably by a UV curable adhesive.Alternatively, if the latching arrangement is utilized for the needleretainer 150, then the spring can bear against the block fixed to theneedle, if desired.

The vial injector 110 includes an actuator 130 that is operable toengage the needle retainer 150 to cause the needle retainer to releasethe insertion needle 114 so that the spring 160 propels the insertionneedle rearwardly. The actuator 130 is an elongated generallycylindrical member having a hollow axial bore 132. The axial bore 132has two diameters. The forward portion of the axial bore has a majordiameter that is larger than the diameter of the rearward portion of theaxial bore. The forward end of the actuator 130 is generally open forreceiving the rearward end of the insertion needle 114 that extends intothe axial bore 132 of the actuator. A mounting stem 138 is connected tothe rearward end of the actuator 130. Preferably, the mounting stem 138is integrally formed with the actuator 130. In the present instance, themounting stem 138 includes an externally threaded portion for threadedlyengaging a plug 190 in the vial 190. A rearward needle 160 for piercingthe plug 190 of the vial 170 projects rearwardly from the mounting stem138. The rear needle 116 is fixedly connected to the actuator 130,preferably by a UV curable adhesive. The forward portion of the rearneedle 114 projects into the axial bore 132 of the actuator 130.Preferably, the rear needle 114 has an internal bore that is larger thanthe external diameter of the insertion needle 114. In this way, theinsertion needle 114 is slidably displaceable within the rear needle116.

As shown most clearly in FIG. 17, a seal 146 provides a fluid tight sealbetween the insertion needle 114 and the rear needle 116. The rearportion of the seal 146 includes a bore sized to receive the forward endof the rear needle 116. The forward portion of the seal 146 includes aconstricted portion sized to receive the smaller diameter insertionneedle 114, providing a fluid tight seal around the external surface ofthe insertion needle.

The forward end 136 of the actuator 130 is configured to cooperate therearward end of the fingers 154 of the needle retainer 150. In thepresent instance, the forward end 136 of the actuator forms a tapered orfrustoconical surface. The rearward end of each needle retainer finger154 tapers radially inwardly so that the rearward end of the needleretainer 150 forms a convergingly tapered annular surface 156.Configured in this way, as shown in FIGS. 14 and 15, when the actuator130 is axially displaced forwardly to engage the needle retainer 150,the cooperating tapered surfaces Of the actuator and the needle retaineroperate as a wedge to displace the needle retainer fingers 154 radiallyoutwardly so that the needle retainer releases the insertion needle 114.The spring 160 then propels the insertion needle 114 rearwardly so thatthe sharpened point of the insertion needle is located within thehousing beyond the reach of the operator.

The vial injector 110 preferably includes at least one, and preferablytwo, safety latches 140 that prevent the actuator 130 from beingdisplaced forwardly until some, and preferably substantially all, of themedication is expelled from the vial 170. Each safety latch 140 isattached to the actuator 130, and in the present instance, the safetylatches are integrally formed with the actuator. Each safety latch 140is a flexible generally L-shaped arm. The forward end of the safetylatch 140 is attached to the actuator 130 and the safety latch extendsrearwardly. Each safety-latch includes a detent 142 that cooperates withan aperture 126 formed in the wall of the barrel 120. In this way, asshown in FIG. 14, when the detent 142 of the safety latch 140 projectsinto the aperture 126, the safety latch 140 prevents the actuator 130from being displaced axially forwardly.

Referring now to FIG. 17, preferably, the forward end of the detent 142and the forward end of the aperture 126 are matingly tapered to improvethe locking engagement of the detent with the aperture. The portion ofthe safety latch rearward of the detent 142 projects radially inwardlytoward the actuator 130, forming a release tab 144. The forward end orrim 172 of the vial 170 cooperates with the release tab 144 to releasethe safety latch 140 as will be discussed further below.

Referring again to FIG. 13, the rearward end of the barrel 120 isgenerally opened, forming a socket 124 for receiving the vial 170. Thevial 170 is a generally cylindrical vessel containing an amount ofmedicinal fluid. The rearward end of the vial 170 is closed, and theforward end of the vial is open forming a rim 172. The open end of thevial 170 is sealed by a rubber piston or plug 190. The plug 190 isgenerally cylindrical having a plurality of axially-spacedcircumferential ribs 192 that form a fluid-tight seal between the plug190 and the internal surface of the vial 170.

The forward or external end of the plug is configured to cooperate withthe mounting stem 138 of the vial injector. In the present instance, themounting stem 138 is externally threaded and the plug 190 hascorresponding internal threads. The interior end of the plug 190adjacent the medication includes a recess 196. In this way, a pierceablewall is formed in the plug 190 between the recess 196 and the base ofthe internal threads. When the vial 170 is mounted on the mounting stem138, the rear needle 116 pierces the wall of the plug and extends intothe recess 196 formed in the interior of the plug. The recess opens tothe interior of the vial 170 so that when the rear needle 116 projectsinto the recess 196, the rear needle is in fluid communication with theinterior of the vial 170, allowing medication to flow from the vial intothe rear needle. After the rear needle 116 pierces the wall of the plug,the wall forms a fluid-tight seal between the plug 190 and the side ofthe rear needle to prevent medication from leaking into the barrel 120.

The medication is expelled from the vial 170 by moving the vial axiallyforwardly to advance the vial. The plug 190 is mounted on the mountingstem 138 so that the plug remains stationary while the vial 170 isadvanced. The plug 190 is configured to form a sliding fit with theinterior of the vial so that the vial 170 can slide over the plug toexpel the medication from the vial. Additionally, the circumferentialribs maintain a fluid-tight seal between the plug and the vial while thevial slides over the plug.

As the vial 170 is advanced, the medication in the vial flows out of thevial and into the rear needle 116. From the rear needle 116, themedication flows into the insertion needle 114 and then into thepatient. After the medication is injected into the patient, theinsertion needle 114 can be retracted into the housing 120 as follows.

Referring now to FIGS. 14-16, when at least substantially all of themedication is expelled from the vial 170, the forward rim 172 of thevial engages the release tab 144 of each safety latch 140. Continuedforward displacement of the vial 170 flexes each safety latch 140,displacing the safety latches radially inwardly thereby withdrawing thedetents 142 from the apertures 126 in the barrel 120. After the detents142 are withdrawn from the apertures 126, continued forward displacementof the vial 170 displaces the actuator 130 axially forwardly. Theactuator 130 then engages the needle retainer 150 to release theinsertion needle 114 as shown in FIG. 17 and described previously. Inthis way, the safety latches 140 prevent the forward axial displacementof the actuator 130 preferably until at least substantially all of themedication is expelled from the vial 170. After at least substantiallyall of the medication has been expelled from the vial 170, the safetylatch 140 releases the actuator allowing the actuator 130 to engage theneedle retainer 150 to release the insertion needle 114.

As shown in FIG. 16, the spring 160 propels the insertion needle 114rearwardly so that the insertion needle telescopes within the rearneedle 116. In addition, as shown in FIG. 16, preferably the barrel 120includes a reduced diameter forward portion forming an internal annularshoulder 125 that engages the forward portion of the safety latches 140.In this way, the internal shoulder 125 acts as a stop to prevent furtherforward axial displacement of the actuator. The terms and expressionswhich have been employed are used as terms of description and not oflimitation. There is no intention in the use of such terms andexpressions of excluding any equivalents of the features shown anddescribed or portions thereof. It is recognized, however, that variousmodifications are possible within the scope and spirit of the invention.For instance, the second embodiment described above can include amanually actuable release for releasing the safety latches 140 so thatthe actuator can be actuated to effectuate retraction beforesubstantially all of the medication is expelled from the vial.Accordingly, the invention incorporates variations that fall within thescope of the following claims.

1. A vial injector, comprising: a housing having an open end oppositefrom a forward end; a vial comprising a fluid container and a plug insealing engagement with an open end of the fluid container, wherein aportion of the fluid container is positioned in the housing with theopen end of the fluid container oriented toward the forward end of thehousing, and a needle having a forward tip movable between a projectingposition in which the forward tip projects forwardly from the housingand a retracted position in which the forward tip of the needle iswithin the housing, wherein a rearward tip is opposite from the forwardtip; a biasing element biasing the forward tip toward the retractedposition; and a needle retainer which releasably engages the housing,wherein the needle retainer is operable between a locked position inwhich the needle retainer releasably retains the needle such that theforward tip is in the projecting position against the bias of thebiasing element and an unlocked position for permitting movement of theforward tip into the retracted position; wherein displacement of thefluid container toward the needle retainer operates to displace theneedle retainer into the unlocked position for permitting retraction ofthe forward tip to the retracted position; and wherein the plug has aseptum which is pierced to provide fluid communication between theneedle and the fluid container and wherein the plug and the needleretainer are coupled so that the plug remains stationary while the fluidcontainer is axially advanced after the septum has been pierced by therearward tip of the needle; and wherein the plug and the needle retainerare configured for one-way engagement to prevent subsequent separationof the plug and the needle retainer.
 2. The vial injector of claim 1wherein the plug and the fluid container remain relatively fixed axiallyrelative to each other during movement of the septum from a poisedposition to a pierced position.
 3. The vial injector of claim 2 whereinthe open end of the fluid container does not move axially relative tothe plug after the septum has been pierced until more force has beenapplied than was necessary to move the septum from the poised position.4. The vial injector of claim 1 wherein the plug includes acircumferential flange which engages an interior surface of the fluidcontainer while the vial is displaced to move the septum from a poisedposition to a pierced position such that the plug and the fluidcontainer remain relatively fixed relative to each other during axialmovement of the septum from the poised position to the pierced position.5. The vial injector of claim 4 wherein the open end of the fluidcontainer moves axially past the circumferential flange of the plugtoward the forward end of the housing as the fluid container is furtherdepressed after the septum has been pierced.
 6. The vial injector ofclaim 1 wherein the needle retainer remains in the locked position asthe plug is moved to advance the septum from a poised position to apierced position.
 7. The vial injector of claim 1 wherein the plug andan interior surface of the fluid container have a sliding fit to expel afluid from the fluid container as the fluid container slides over theplug.
 8. The vial injector of claim 1 wherein the open end of the fluidcontainer moves axially past the plug toward the forward end of thehousing as the fluid container is further depressed after the septum hasbeen pierced by the rearward tip of the needle.
 9. The vial injector ofclaim 1 wherein the plug is configured to prevent ejection of fluid whenthe plug is moved to advance the septum from a poised position to apierced position.
 10. The vial injector of claim 1 wherein the needleretainer comprises a latch biased radially outwardly to releasablyengage the housing.
 11. A vial injector, comprising: a housing having anopen end opposite from a forward end; a vial comprising a fluidcontainer and a plug in sealing engagement with an open end of the fluidcontainer, wherein a portion of the fluid container is positioned in thehousing with the open end of the fluid container oriented toward theforward end of the housing, and wherein the plug comprises a socketwhich terminates at a pierceable septum; a needle having a forward tipmovable between a projecting position in which the forward tip projectsforwardly from the housing and a retracted position in which the forwardtip of the needle is within the housing, wherein a rearward tip isopposite from the forward tip; a biasing element biasing the forward tiptoward the retracted position; and a needle retainer which releasablyengages the housing, wherein the needle retainer is operable between alocked position in which the needle retainer releasably retains theneedle such that the forward tip is in the projecting position againstthe bias of the biasing element and an unlocked position for permittingmovement of the forward tip into the retracted position; whereindisplacement of the fluid container toward the needle retainer operatesto displace the needle retainer into the unlocked position forpermitting retraction of the forward tip to the retracted position; andwherein the needle retainer has a mounting stem which is configured tobe received in the socket of the plug as the plug is moved to advancethe septum from a poised position for being pierced by the rearward tipof the needle to a pierced position with the rearward tip of the needleextending through the septum to provide fluid communication between thefluid container and the needle.
 12. The vial injector of claim 11wherein the socket has two radially relieved portions, and wherein themounting stem has a barb with a shoulder configured to mate with the tworadially relieved portions.
 13. The vial injector of claim 12 whereinthe shoulder is configured for one-way engagement with the two radiallyrelieved portions.
 14. The vial injector of claim 11 wherein the plugand the fluid container remain relatively fixed axially relative to eachother during movement of the septum from the poised position to thepierced position.
 15. The vial injector of claim 14 wherein the open endof the fluid container does not move axially relative to the plug afterthe septum has been pierced until more force has been applied than wasnecessary to move the septum from the poised position.
 16. The vialinjector of claim 11 wherein the plug includes a circumferential flangewhich engages an interior surface of the fluid container while the vialis displaced to move the septum from a poised position to a piercedposition such that the plug and the fluid container remain relativelyfixed relative to each other during axial movement of the septum fromthe poised position to the pierced position.
 17. The vial injector ofclaim 16 wherein the open end of the fluid container moves axially pastthe circumferential flange of the plug toward the forward end of thehousing as the fluid container is further depressed after the septum hasbeen pierced.
 18. The vial injector of claim 11 wherein the plug and theneedle retainer are configured for one-way coupling.
 19. The vialinjector of claim 11 wherein the needle retainer remains in the lockedposition as the plug is moved to advance the septum from the poisedposition to the pierced position.
 20. The vial injector of claim 11wherein the plug and an interior surface of the fluid container have asliding fit to expel a fluid from the fluid container as the fluidcontainer slides over the plug.
 21. The vial injector of claim 11wherein the open end of the fluid container moves axially past the plugtoward the forward end of the housing as the fluid container is furtherdepressed after the septum has been pierced by the rearward tip of theneedle.
 22. The vial injector of claim 11 wherein the plug is configuredto prevent ejection of fluid when the plug is moved to advance theseptum from a poised position to a pierced position.
 23. The vialinjector of claim 11 wherein the needle retainer comprises a latchbiased radially outwardly to releasably engage the housing.